Microelectrodes are electrodes with micrometer-level (1×10−6 m) to nanometer-level (1×10−9 m) linear dimension. As the linear dimension of an electrode is reduced from millimeter level to micrometer level, the electrode will exhibit many outstanding electro-chemical properties. For example, thanks to the tiny electrode size, microelectrodes are favorable for in-situ analysis; more importantly, microelectrodes have incomparable advantages over conventional electrodes, i.e., very high steady-state current density, very short response time, low polarization current, low IR drop, high mass transfer rate, high signal-to-noise ratio, support for transient electrode process study, high-impedance electrolyte and flow system. A microelectrode array is an array of monotonously arranged electrodes bundling by multiple microelectrodes, and the current flowing is the sum of currents flowing through the individual electrodes. The electrodes in a microelectrode array have the same properties as the original individual electrodes, and higher current intensity can be obtained; thus, the sensitivity of measurement is improved.
Recently, microelectrode arrays have drawn wide attention, as they have been widely applied in the fields of microelectronic circuit, bio-sensor, and micro-fluid, etc. At present, existing methods for preparing microelectrode arrays are mainly based on a top-down technique developed oversea, i.e., a silicon wafer is etched with focused laser to obtain an array of microelectrode pairs (Clendenning S B, Aouba S, Rayat M S, Grozea D, Sorge J B, Brodersen P M, Advanced Materials, 2004, vol. 16, p 215). However, such methods require expensive and complex preparation instruments, and the sample preparation process is time-consuming and inefficient. Another type of methods covers wet chemical methods (based on solvent evaporation self-assembly technique) (Ryu D Y, Shin K, Drockenmuller E, Hawker C J, Russell T P. Science, 2005, vol. 308, p 236), i.e., water or an organic solvent that contains nanowires or water or an organic solvent containing a substance that can form nanowires is spread on the silicon wafer electrode surface with a micro-pillar array; as the water or organic solvent volatilizes rapidly, the nanowires will be self-assembled to the electrode tips of the micro-pillar array. Though such methods overcome the drawback of long preparation time required for preparing an array of microelectrode pairs, the assembly result is unsatisfactory, i.e., defects often occur and local defects are often formed as a result of surface adhesion. Therefore, a preparation method that can be used to quickly produce a microelectrode array that is large in area, free of adhesion, with adjustable and controllable dimension of nanowires is required in the production of microelectrode arrays.